Drawbench gripper carriage



Feb. 8, 1944.

D. W. T. EVANS DRAW BENCH GRIPPER CARRIAGE Filed Nov. 1'7, 1942 Feb. 8, 1944.] D. w. T. EVANS DRAW BENCH GRIPPER CARRIAGE 2 Sheefs-Sheef 2 Filed Nov. 17, 1942 III/06.31102 If. TEvalns W UNHTED STATES @LFFEQE DRAWBENCH GRIPPER CARRIAGE David William Thomas Evans, Sutton Coldfielcl, England, assignor to T. I. (Group Services) Limited, Birmingham, England Application November 17, 1942, Serial No. 465,875 In Great Britain November 21, 1941 1 Claim.

This invention relates to the carriages used on draw benches for drawing tubes or other workpieces through dies, the carriages being of the kind having grippers in th form of a pair of slidable jaws adapted to grip between them the forward end of the workpiece or a pulling pin attached to the workpiece. The object of the present invention is to facilitate proper engagement of the workpiece or pulling pin with the grippers at the commencement of the drawing operation.

In the accompanying sheets of explanatory drawings:

Figure 1 is a sectional plan of a part of a draw bench gripper carriage provided with the invention, the grippers being shown in their open or inoperative positions.

Figure 2 is a similar view to Figure 1 showing the grippers in their closed or operative positions.

In the drawings a indicates the carriage which is movable along a draw bench, and indicates the grippers which are adapted to grip between them the forward end of a pulling pin d attached to the workpiece e. The grippers c consist of a pair of jaws which are slidably mounted in the rear end of the carriage a, the outer sides of the jaws and the adjacent parts of the carriage being formed with correspondingly inclined surfaces 1, g, which by contact with each other cause the jaws to approach each other during sliding movement in one direction, and to recede from each other during sliding movement in the opposite direction. Any convenient means (not shown) are employed for actuating the grippers c. The pulling pin d is formed with a screw thread h for engagement by complementary screw threads 2' on the grippers c. When the pullin pin :2 is engaged by the grippers c, movement of the carriage a in the appropriate direction causes the workpiece e to be drawn through a die 7' in a holder 70 on the draw bench.

In applying the invention to the carriage a, I secure to the rear end of the carriage near the entrance to the grippers c a strong plate m, this being spaced from the said end by short distance pieces 11. In the centre of the plate is formed a hole in which is mounted an annular holder 10 for a bell-mouthed hollow guide piece q, the latter having a screw thread connection with its holder, and being such that the adjacent end of the pulling pin d can pass through it into a central position between the grippers c. The

guide piece q and its holder 10 are capable of umcient axial movement relatively to the plate m to enable the holder to make contact with and exert pressure on the adjacent ends of the gripgers 0 when the latter are in their closed or 0perative positions. For this purpose in the example shown, the guide piece holder p is free to slide in the hole in the plate m to an extent determined in one direction by contact of the guide piece q with one side of the plate, and in the opposite direction by contact of a lip or flange r on the holder with the other side of the plate. In the event of the grippers c sticking after the work piece 6 has passed through the die 7', a blow on the guide piece q will efiect release of the grippers.

When the carriage a (during its return movement on the draw bench) approaches its initial position near the die 7' the forward end of the pulling pin d which has already been inserted through the die is encountered by the bellmouthed end of the guide piece q (as shown in Figure 1) and is thereby centralised, thus enabling the said end to be properly located between the grippers 0.

Instead of being adapted to grip a pulling pin as above described the grippers may be adapted to grip the workpiece in which case the latter is centralised by the guide piece.

By this invention I am able to ensure proper location of the workpiece or pulling pin end between the grippers and obviate in a very satisfactory manner the operational difiiculties which are otherwise liable to be encountered.

The invention is not limited to the example above described as subordinate details may be varied to suit requirements.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

A draw bench gripper carriage having in combination grippers in the form of a pair of slidable jaws adapted to grip between them the forward end of the workpiece or a pulling pin attached to the workpiece, and having combined with the rear end of the carriage adjacent to the entrance end of the grippers, a bell-mouthed guide piece adapted by abutting against the forward end of the workpiece or pulling pin to centralise it relatively to the grippers, the guide piece being capable of a limited axial movement relatively to the carriage for releasing the grippers.

DAVID WILLIAM THOMAS EVANS. 

